Stylistically, I love the way we get these glimpses of him, through other people's accounts. It is in such contrast to how we are practically inside Anne's head.

I do not see his trait as 'reckless impetuousness', though I can see why Lady Russell would. I see him as someone able to judge, and willing to take, risks. Because he has no background resources (no connections), he has had to do this all his life. The one time we know of it not working was the engagement, and that was because Anne could not take the risk with him.